The invention discloses a multi-wavelength line-scanning Raman spectrometer. The Raman spectrometer comprises a laser light source, a focusing objective lens, a first diffraction grating, a long-wave-pass optical filter group and a spectrum collection unit, wherein the laser light source comprises a laser device, a beam coupling system and an attenuation piece and is used for outputting exciting light to a sample; the focusing objective lens and the first diffraction grating are used for realizing the transverse line scanning of the Raman spectrometer to the sample; the long-wave-pass opticalfilter group is used for filtering out exciting light output by the laser light source; and the spectrum collection unit comprises a lens group, a second diffraction grating and a CCD and is used forcollecting and processing Raman light scattered on different transverse positions of the sample. By combining the diffraction gratings with a focusing lens, the line distribution of light of differentwavelengths on the cross section of the sample is realized, and the transverse line scanning of the Raman spectrometer to the sample is realized, so that the line scanning based on a displacement platform is avoided, and the dimension of a system is reduced; and by demodulating spectra with close wavelengths, the fluorescence background of the sample can be removed, and the accuracy of a detection result can be improved.